This invention relates to container-filling machines of the type wherein a metered amount of liquid material is discharged downwardly from a filling spout into an open-topped container.
Machines of this type typically have a fixed filler spout and a conveyor mechanism for bringing a container to the spout so that the container may be filled. When the liquid material is of a non-foaming character, the container can be positioned so that its open top is below the bottom end of the spout and the material can be discharged from the spout into the container with little difficulty. In such case, since the spout is completely above the container, a valving mechanism and valve operator therefor can be mounted at the lower end of the spout to prevent drips after a container has been filled and during the time that a new, empty container is being moved into place to be filled.
Many liquid materials, however, are of such nature that the discharge of the material from the elevated spout into the container will cause the material to foam during the filling operation. If the foaming is sufficiently severe it will be difficult or impossible to fill the container with the desired amount of the liquid.
In order to prevent such foaming, container-filling machines are provided with an elevator table below the filler spout. The conveyor mechanism brings a container to the elevator table and positions the open top of the container beneath the spout. The elevator table then raises the container relative to the fixed spout so that in effect the spout descends down into the container until the bottom end of the spout is closely adjacent the bottom of the container. The material may then be discharged from the spout with minimum agitation and foaming. After filling, the elevator table lowers the filled container back down below the spout so that it can be removed and a new container can be brought into place.
Since it is necessary for this bottom-up filling method that the spout be inserted within the container, space and contamination considerations prevent the use of the conventional valve and valve actuator at the bottom of the spout. Operation with an elevator table and without a cut-off valve on the bottom of the spout has been acceptable for heavy, viscous materials such as spackling paste, mayonnaise or similar products that will hold in the spout due to its thickness or viscosity. Such operation, however, is not very satisfactory for filling with thin materials of low viscosity since some of such material will drain from the open bottom of the spout during the time that the filled container is being removed and the new container is being brought into place. Such drainage will cause contamination of the conveyor and containers. In some instances the contamination may be simply an undesirable nuisance. In other instances, such as where poisonous or corrosive materials are being handled, such drippage cannot be tolerated.